How will upper low WSW of Katrina affect her, if at all?

[Stormcenter]

How will upper low WSW of Katrina affect her movement, if at all?

http://www.rap.ucar.edu/weather/satelli ... duration=6

[Ixolib]

How will upper low WSW of Katrina affect her movement, if at all?

http://www.rap.ucar.edu/weather/satelli ... duration=6

Was kinda wondering that myself a little earlier... Glad you posted this.

[Steve]

Usually then tend to shear storms (or provide outflow depnding on their compass point relationship), but in this case, I don't think the low will have much impact. Ordinarily when an upper low is SW and puts distance between the two, the environment improves on the southern and western quadrants of a system as stability/upper high pressure tends to take the place of the upper-level lower pressure. Hope that helps some. (A pro met or qualified amateur could better explain the different entrance regions into the jetstream depending on the juxtapositioning between a tropical cyclone and and uppper low pressure which in some cases is beneficial to a strenghtening or mature storm).



Steve

[Javlin]

hey Steve once you mentioned the the 4 quadarnts and the effect mind explaining again

[stormcloud]

Since the low is backing away, its effect will be minimal. An upper low can either shear a system or ventilate it. As the upper low in the Gulf backs away, it will help ventilate Katrina and that may be a step toward strengthening.

[MWatkins]

Other than venting the upper level outflow...little to no effect. Amazing how that feature got out of the way in the last 12/18 hours.

MW

[Steve]

I don't want to screw it up by saying it backwards, so if I have it backwards, hopefully someone will correct me. But I think the NW and SE Quadrants are positioned so that the flow literally provides exhaust into the jetstream while the NE and SW quads tend to blow at the systems and disrupt them. I don't understand physics, thermodynamics or the properties of liquids and gasses so this isn't technical, but what happens up at 'x' feet (too late to research how high up) is that the storm is able to exhaust outflow into usually an upper westerly channel which my guess allows the continued momentum of the core to spin at whatever velocity is available. Think of the upper low in the right postition as a tailpipe I guess.

Again, hope that helped. But I haven't read on that stuff in a long time. It might be the SW/NE quads that are beneficial. But like I said, hopefully someone can set the record straight and explain this stuff better than I.

Steve

[wxmann_91]

Perhaps what the models are hinting at (only short time in GOM, more northward motion) has something to do with ULL. Remember Irene? According to some here, UKMET was "plowing through the ridge" but the ULL nearby induced a weakness that Irene got caught into, thus saving the Carolinas from a hit.

So maybe that is what the ULL will do.

[artist]

welcome stormcloud!

[btangy]

The ULL actually helped the development of Katrina by shielding it from the shear on the SE side of a strong upper level hi over the C Gulf. Once the low backed away, it actually created some very strong divergence aloft as evident by the very strong spreading of the cirrus today.

I'm having trouble seeing what dry air there is around Katrina. There's a bunch of convection bubbling up all around Katrina's core, which is something you often see with quickly developing storms and is not indicative of any dry air. The frontal system remains far the the north and any dry air is confined well NE of the system. Of course, there still may be dry air in the mid-levels which WV imagery cannot pick up.

[MWatkins]

The ULL actually helped the development of Katrina by shielding it from the shear on the SE side of a strong upper level hi over the C Gulf. Once the low backed away, it actually created some very strong divergence aloft as evident by the very strong spreading of the cirrus today.

I'm having trouble seeing what dry air there is around Katrina. There's a bunch of convection bubbling up all around Katrina's core, which is something you often see with quickly developing storms and is not indicative of any dry air. The frontal system remains far the the north and any dry air is confined well NE of the system. Of course, there still may be dry air in the mid-levels which WV imagery cannot pick up.

Excellent observations as always...sure wish the eclipse wasn't there...but recon will be out there shortly.

It's possible that dry air could be getting confused with subsiding air around the bursts. Regardless...the inner core continues to get better organized and there is a good chance we will see a hurricane make landfall in SFL by Friday...

Sure wish you would post more, btangy...

MW

[HurricaneBill]

Upper Level Lows can do 3 things:

1. Shear a storm apart (Claudette 2003)

2. Strengthen a storm (Alex 2004)

3. Become a tropical cyclone themselves (Beryl 1994)

Just out of curiosity, what was the strongest storm to originate from an upper level low?

[weatherSnoop]

I cannot answer that question, but Katrina does seem to tighten up a bit in the wee hours.

http://www.meteo.psu.edu/~gadomski/SAT_ATL/anim8wv.html

not The most recent images, but a full view of the surrounding environment a few hours ago